<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>圣杯布局</title>
    <style>
        body {
            margin: 0;
            padding: 0;
        }
        .left, .right, .main {
            height: 100px;
            float: left;
        }
        .wrap {
            padding: 0 200px 0 300px;
        }
        .wrap::after{
            content: '';
            display: block;
            clear: both;
        }
        .main {
            width: 100%;
            background-color: red;
        }
        .left {
            width: 300px;
            position: relative;
            left: -300px;
            background-color: green;
            margin-left: -100%;
        }
        .right {
            width: 200px;
            position: relative;
            right: -200px;
            background-color: pink;
            margin-left: -200px;
        }
        @media screen and (max-width: 1000px) {
            .wrap {
                padding: 0;
            }
            .left {
                margin-left: 0;
                left: 0;
            }
            .right {
                margin-left: 0;
                right: 0;
            }
        }
    </style>
</head>
<body>
    <div class="wrap">
        <div class="main">main</div>
        <div class="left">left</div>
        <div class="right">right</div>
    </div>
</body>
</html>